The present invention generally relates to devices and processes for collection and testing of fluid specimens, and more specifically relates to a device and process for lateral flow testing of oral fluid, for example saliva.
Unlike other forms of fluid specimens such as blood or urine, collection of oral fluid, for example saliva, for diagnostic purposes is complicated by many factors, for example, the low volumes of salivary fluid secreted into the oral cavity, the relatively high viscosity thereof, and the diverse anatomic dispersion of the salivary glands. Most techniques for collection involve the use of capillary tubes, suction into micropipettes, chewing on paraffin or foam, and/or aspiration from the mouth into polypropylene syringes.
Conventional, commercially available lateral flow test strips ( i.e. nitrocellulose strips) have long been used for diagnostic testing of bodily fluids such as urine. These devices are inexpensive and produce reliable results for many applications. These same test strips however are not conventionally used for testing oral fluids such as saliva. It is known that when saliva is applied to a sample pad of a commercially available urine testing lateral flow test strip, the saliva sample does not run. It is believed that this is due to the relatively high concentrations of mucin and other viscous, proteinaceous materials in the specimen.
In addition, testing of salivary specimens has not been extensively developed. Until relatively recently, blood and urine samples were the primary fluids used for testing for disease as well as for evidence of substance abuse. However, it is known that human saliva carries lymphocytes, plasma cells and immunoglobulins that are directly related to the immunoglobulins found in the blood. In addition, saliva carries immunoglobins that are believed to be peculiar to saliva, for example, the antibody known as secretory IgA. Because of the association between immunoglobulins of the blood and saliva, as well as the occurrence of secretory IgA, antigen-antibody tests have been conducted on salival fluid to assess the value of such tests as screening tools for disease.
U.S. Pat. No. 5,922,614 to Cesarczyk describes a Sample Collection Method with Extraction Sleeve. The device is designed for collecting saliva or urine samples using an absorbent, elongate foam member secured in a hollow tube with one portion extending therefrom. The foam member is used to absorb a fluid specimen. The foam member and hollow tube are slidably mounted within a flexible sleeve to cover the foam member as well as provide a means for extracting the fluid from the foam by exerting pressure on the sleeve to compress the foam member to release the fluid. According to Cesarczyk, the device provides an aseptic, easy to use device for collecting a fluid sample such as saliva.
Accordingly, a method and device are provided for diagnostic testing of an oral fluid, such as saliva or other proteinaceous fluid specimen.
The device generally comprises a housing including well means for receiving a fluid specimen, and testing means, at least partially encased within the housing, for enabling diagnostic testing of the fluid specimen received in the well means. The testing means includes a diagnostic test strip including a sample portion and a test portion for visually indicating test results and test validity.
Advantageously, the device further comprises means for disassociating proteinaceous material from the fluid specimen, for example a membrane or pad having deposited thereon a salt or other known mucinolytic substance known to break down and lower the viscosity of mucin-containing fluids. The pad is preferably comprised of a glass fiber matrix which provides means for filtering the disassociated proteinaceous matter and other particulate material from the specimen. These features of the present invention function to facilitate migration of an originally viscid, mucin containing fluid specimen, such as saliva, without any pretreatment steps. The device allows convenient and rapid testing of a relatively small saliva sample without any need to pre-treat the saliva in order to enable its migration along the test strip.
The salt pad may be positioned to overlay a portion of the sample portion of the test strip. The test strip is encased within the housing such that the salt pad is in fluid communication with the well means.
The present invention further includes a process for lateral flow saliva testing, generally comprising the steps of providing a lateral flow test strip having a sample portion and a test portion, providing a pad having a material capable of disassociating proteinaceous materials in an oral fluid, for example a salt, positioning the pad along the sample portion of the lateral flow test strip, depositing an oral fluid specimen on the pad positioned on the lateral flow test strip, and allowing proteinaceous materials in the specimen to substantially disassociate from the specimen to facilitate migration of the specimen into the test portion of the lateral flow test strip as a relatively mucin-free specimen.